Stabilizer for overrunning thermostatic controls



1953 H. A. CARLSON ETAL STABILIZER FOR OVERRUNNING THERMOSTATIC CONTROLS Filed Dec. 7, 1950 ATTORNEY Patented Nov. 3, 1953 STABILIZER FOR OVERRUNNING THERMO- STATIC CON TROLS Harold A. Carlson,

Brentwood, and James T. W.

Moseley, Richmond Heights, Mo., assignors to Carter Carburetor Corporation,

St. Louis, Mo.,

a corporation of Delaware Application December 7, 1950, Serial No. 199,672

4 Claims.

This invention relates to thermostatic control units of the overrunning or one-way type and consists particularly in novel means for stabilizing such units during the overrun portions of their actions when they are separated from the members they control.

An example of the above type of thermostat occurs in a well known automatic choke control for automotive carburetors. Such control, as

illustrated, for instance, in Coifey Patent No. 1

2,085,351, embodies a bimetal thermostatic coil having a shiftable, outer extremity with a oneway operative connection to an arm movable with the choke valve, so that when the thermostat flexes, as the temperature drops, this arm and the choke valve are yieldingly urged toward closed position. However, when the thermostat flexes in the opposite direction, under the influence of rising temperatures, the outer operating extremity thereof tends to move away from the choke valve arm, permitting opening of the choke valve under the influence of direct action of suction thereon. Ultimately, the thermostat extremity separates from the choke valve k arm so that the thermostat will not be unduly strained at high temperatures. During the period when the thermostat extremity is separated from the choke valve arm and unsupported, an unpleasant tapping or hum may be produced due to vibration of the extremity against an adjacent part.

The main object of the present invention is to provide means for stabilizing the outer extremity of the thermostat coil so as to avoid this unpleasant vibration sound.

This object and other more detailed objects hereafter appearing are attained by the structure illustrated in the accompanying drawing in which Fig. 1 is a side view, partially sectioned, showing a portion of an internal combustion engine manifold with a carburetor mounted thereon.

Fig. 2 is an enlarged, partial section taken approximately on line 2-2 of Fig. 1.

Fig. 3 is a side view of the thermostat housing partition removed.

Fig. 4 is a section on line 4-4 of Fig. 3.

Fig. 5 is a side view of the thermostat and partition, the choke valve being shown in full open position.

Fig. 6 is an edge view of the parts in Fig. 5.

Fig. '7 is a view similar to Fig. 5, but showing the thermostat in its overrun position.

Fig. 8 is an edge view of the parts in Fig. '7.

Figure 1 shows a portion 10 of the intake manifold of an automotive internal combustion engine which extends into a hot spot ll upon which is mounted a downdraft carburetor l2 by means of a flange l3 at the lower end thereof. At the upper end of the carburetor is an air inlet horn l4 within which is an unbalanced, butterfly choke valve l5 for controlling the admission of air to the carburetor and, accordingly, the richness of the fuel mixture supplied to the engine thereby. At the lower end of the carburetor is a butterfly type throttle valve l6 having an arm ll rigid therewith for attachment to the usual accelerator controls conveniently located for operation by the driver.

Mounted on air horn I4 is a cup-like housing having a cover 2| of insulating material adjustably secured thereto by means of wing clips 22. Choke shaft 23, upon which choke valve disk I 5 is mounted, projects into this housing and carries an arm 24 rigid therewith inside the housing. A bimetal thermostat coil 25 is centrally secured to a pintle 26 projecting inwardly from the housing cover and has a free outer extremity formed with a hook 21. Traversing the housing is a baffle disk 28 having an arcuate slot 29 through which projects a finger 30 on choke shaft arm 24. This finger is in position to be engaged by extremity 2! on the thermostat coil, during counterclockwise movement of the hook (Fig. 1), to urge the choke valve closed. Such movement of hook 21 is produced by a lowering of the temperature within the housing which, in effect, causes the thermostatic coil to unwind. Upon raising of the temperature, the thermostat coil is caused to further wind upon itself, whereupon hook 2! shifts in a clockwise direction permitting the unbalanced choke valve to open by its own Weight and by the influence of air drawn in through the carburetor by operation of the engme.

Figure 5 shows the choke valve in its fully open position, and with thermostatic hook 21 just separated therefrom. In Figure 7, the thermostat is further heated so that hook 21 has moved a considerable distance beyond finger 30. This overrun is customary and desirable so that the thermostat will not be placed under undue strain upon increases of temperature above that at which the choke should be fully open.

A second arm 32 on the choke valve shaft between the air horn and housing 20 is connected by a link 33 to acam 34 pivotally mounted on the carburetor body adjacent the throttle valve. Operating arm I! on the throttle valve carries an abutment screw 35 for engaging the cam to vary the limit of closing movement of the throttle valve. Cam 34 is moved, when the choke valve is closed, to a position to limit the closing of the throttle valve to a fast idle position and, when the choke valve is fully open, permits closing of the throttle valve to its normal idling position.

A stove 31 is mounted on a portion of the manifold for supplying hot air to a tube 38 which extends to the interior of housing 20. Hot air is drawn from the stove through the housingand past the thermostat by engine suction which is transmitted to the interior of the housinz past suction piston 39. This piston, as explained in the above mentioned Patent No, 2,086,351, re sponds to suction in the engine intake posterior to the throttle, to bias the choke toward open position. The stove and hot air connection tend to make the thermostat closely responsive to the actual engine temperature, so that the position of the choke valve and, consequently, the riohness of the mixture islikewise responsive to enzine temperature.

In order to prevent the free extremity of the thermostatic coil from vibrating. against baflie disk 28 when the engine-is inoperation, which may produce an unpleasant hum or buzzing sound,vthe-bailie disk is providedwitha restricted, outlet. portion 40 f general arcuate contour and inclined circumferentially to the plane ofthe disk, as indicated in Figs. 6' andS; and also inclined radially, as indicated in Fig. 4. This outset ramp is-positioned in the path of hook 21 on the thermostat coil sothat-just as the hook'leaves finger 30- (Fig. it comes into-engagement with the ramp and, thereafter, during its continued overrun the hookis distorted somewhat, as indicated in-Fig. 8; 'Ihe'ramp, thus,.applies a'stabilizing stress to-the hook and, of course, eliminates rapid striking of the disk bafile thereby and resulting buzzing or humming sound.-

A further advantage is that the transference of: heat to-the thermostat from the metalof the carburetor is facilitated so that the cooling'thereof is delayed after the enginestops.

The exact shape'and disposition of the stabil izing structure 40 and its manner of mounting, maybe varied as expedient and-so as to properly cooperate with the particular type-of overrunnins, control. The inventionis especially'advantageous when used in connection with the automatic choke control thermostat of a carburetor, as-illustrated, but may be-applied to other types of controls having a similar manner of functioninz.

The exclusive use of all modifications as come withinthe scope of the. appended claims is contemplated.

We claim:

1. A thermostatic control comprising a movthereof, said extremity able thermostatic element, a device operable by said element and having a one-way operative connection therewith whereby said element, in one position thereof, may operate said device and, in another position thereof is separated from said device, and I! ramp member located in the path of the latter part of 6b movement o said element for frictional engagement thereby to stress and stabilize said element.

2. A thermostatic control comprising a coiled thermostatic spring having an outer extremity rotatable under temperature changes, a device operable by said coil and having a one-way operating connection with said outer extremity being rotatable beyond and deviceafter the limit of movement of said device, and a ramp member located in the path of movement of said extremity after separation from said device for frictional engagement by said extremity to stress' and stabilize the same.

3; A thermostatic control unit comprising a bimetal thermostatic coil having a rotatable, laterally resilient outer extremity, a device with which said coil cooperates and positioned to' be engaged by said extremity during a portion of its movement in one direction and toseparat'e from said device during a portion ofits movement in the opposite direction, and an inclined member disposed to be. engaged by said extremity after separation from said device for distorting and stabilizing'the same.

4-5 A thermostatic control unit comprising a thermostatic coil spring having a me; movable outer extremityg-a device'havinga-one way operativ connection with said extremity for movement thereby during a part of the movement of said extremity, saidextremity separating from saiddevice'duringanother part-of the movement thereof, and a disk mounted adjacent and parallel to'said spring andhaving a ramp forming part projecting into the path of said extremity for frictional engagement thereby, upon separation from said'device, to applystabilizing stress to said extremity.

HAROLD A. CARL-SON. JAMES- T. W. MOSELEY;

References- Cited in the file of this patent um'rnn s'ra'rss Pxrmrrs' 

